Destroying charged black holes in higher dimensions with test particles

2017 ◽  
Vol 32 (21) ◽  
pp. 1750125 ◽  
Author(s):  
Bin Wu ◽  
Weiyang Liu ◽  
Hao Tang ◽  
Rui-Hong Yue
Keyword(s):  
Black Hole ◽  
Naked Singularity ◽  
Cosmic Censorship ◽  
Point Particle ◽  
Test Point ◽  
Extremal Black Hole ◽  
Charged Black Holes ◽  
Test Particles ◽  
Gedanken Experiment ◽  
Self Force

A possible way to destroy the Tangherlini Reissner–Nordström black hole is discussed in the spirit of Wald’s gedanken experiment. By neglecting radiation and self force effects, the absorbing condition and destruction condition of the test point particle which is capable of destroying the black hole are obtained. We find that it is impossible to challenge the weak cosmic censorship for an initially extremal black hole in all dimensions. Instead, it is shown that the near extremal black hole will turn into a naked singularity in this particular process, in which case the allowed range of the particle’s energy is very narrow. The result indicates that the self-force effects may well change the outcome of the calculation.

scholarly journals Weak cosmic censorship conjecture in Kerr black holes of modified gravity

2019 ◽  
Vol 34 (05) ◽  
pp. 1950037 ◽  
Author(s):  
Bin Liang ◽  
Shao-Wen Wei ◽  
Yu-Xiao Liu
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Lower Energy ◽  
Energy Gap ◽  
Naked Singularity ◽  
Cosmic Censorship ◽  
Point Particle ◽  
Adiabatic Process ◽  
Energy Bounds ◽  
Cosmic Censorship Conjecture

By neglecting the effects of self-force and radiation, we investigate the possibility of destroying the Kerr-MOG black hole through the point particle absorption process. Using the instability of event horizon and equation of particle motion, we get the upper and lower energy bounds allowed for a matter particle to produce the naked singularity. We find that the energy gap always exists between the upper and lower energy bounds for both extremal and near-extremal black holes, which means some tailored particles can actually lead to the violation of the weak cosmic censorship conjecture. However, when considering the effect of the adiabatic process, the result shows that the Kerr-MOG black hole gets more stable instead of a naked singularity, and thus the weak cosmic censorship conjecture can be restored at some level.

scholarly journals Over-spinning Kerr–Sen black holes with test fields

2019 ◽  
Vol 28 (02) ◽  
pp. 1950044 ◽  
Author(s):  
Koray Düztaş
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gordon Equation ◽  
Naked Singularity ◽  
Weak Form ◽  
Scalar Fields ◽  
Cosmic Censorship ◽  
Extremal Black Hole ◽  
Klein Gordon ◽  
Fermionic Fields

In this work, we investigate validity of the weak form of the cosmic censorship conjecture in the interaction of Kerr–Sen black holes with neutral test fields. Previous studies of the Klein–Gordon equation on Kerr–Sen background imply that superradiance occurs for scalar fields. We show that scalar fields can overspin a nearly extremal black hole into a naked singularity, but the modes that could overspin an extremal black hole are not absorbed due to superradiance. From Kerr analogy one can naively expect superradiance to be absent for fermionic fields. In such a case overspinning becomes generic and also applies to extremal Kerr–Sen black holes. This robust violation of cosmic censorship cannot be fixed by backreaction effects which are ignored in this work. These results are analogous to the Kerr case.

Cosmic Censorship!: Thermal Transport in a ‘Naked’ Black Hole

2011 ◽  
Vol 312-315 ◽  
pp. 27-32
Author(s):  
R. Leticia Corral Bustamante ◽  
Aarón Raúl Rodríguez-Corral ◽  
T.J Amador-Parra ◽  
E.A. Vázquez-Tapia
Keyword(s):  
Black Hole ◽  
Angular Momentum ◽  
Event Horizon ◽  
Naked Singularity ◽  
Major Axis ◽  
Cosmic Censorship ◽  
Einstein Equations ◽  
Semi Major Axis ◽  
High Entropy ◽  
Apparent Horizons

Cosmic censorship!: black hole wrapped up by its entropy and hidden by its event horizon. In this paper, we postulate a metric to solve the Einstein equations of general relativity, which predicts the thermodynamic behavior of a gigantic mass that collapses to a black hole; taking into account the third law of thermodynamics that states that neither physical process can produce a naked singularity. However, under certain conditions, the model allows to evident violation to the cosmic censorship, exposing the hole nakedness. During the collapse of the hole, quantum effects appear: the area decrease and radiation produced has a high entropy, so that increases total entropy and expose the presence of the hole, while the appearance of the event horizon hide the singularity of the exterior gazes. It is verified that in certain circumstances, the model predicts that the hole mass is bigger than its angular momentum; and in all circumstances, this predicts an hole with enormous superficial graveness that satisfy a relationship of the three parameters that describe the hole (mass, charge and angular momentum); factors all indicative that the singularity is not naked. Then, there are no apparent horizons in accord with cosmic censorship conjecture. Even though the surface gravity of the hole prevents destroying its horizon wrapping singularity, there exists evidence of this singularity by the results of the spin-mass relationship and the escape velocity obtained. The lost information and the slow rate of rotation of the semi-major axis of the mass (dragging space and time around itself as it rotates), agree with Einstein's prediction, show the transport of energy through heat and mass transfer, which were measured by entropy of the hole by means of coordinated semi-spherical that include the different types of intrinsic energy to the process of radiation of the hole event horizon.

scholarly journals Improved Reissner–Nordström–(A)dS black hole in asymptotic safety

2016 ◽  
Vol 31 (26) ◽  
pp. 1650141 ◽  
Author(s):  
Cristopher González ◽  
Benjamin Koch
Keyword(s):  
Black Hole ◽  
Einstein Gravity ◽  
Cosmic Censorship ◽  
Black Hole Mass ◽  
Crucial Point ◽  
Group Approach ◽  
Functional Renormalization Group ◽  
Charged Black Holes ◽  
Renormalization Group Approach ◽  
Cosmic Censorship Hypothesis

This paper studies the quantum modifications of the Reissner–Nordström–(A)dS black hole within Quantum Einstein Gravity, coupled to an electromagnetic sector. Quantum effects are introduced on the level of the improvements of the classical solution, where the originally constant couplings ([Formula: see text], [Formula: see text] and [Formula: see text]) are promoted to scale dependent quantities ([Formula: see text], [Formula: see text] and [Formula: see text]). Those running couplings are calculated in the functional renormalization group approach. A crucial point of this so-called “improving solutions” procedure is the scale setting where the arbitrary scale [Formula: see text] acquires physical meaning due to a relation to the coordinate scale [Formula: see text]. It is proposed to use such scale settings which are stable after iterative improvements. Using this method one finds that for those improved solutions, there is no stable remnant and due to the appearance of a new internal horizon, there is also no necessity to impose a minimal black hole mass for charged black holes, in order to avoid the cosmic censorship hypothesis.

scholarly journals ENTROPY OF EXTREMAL DYONIC BLACK HOLES

1996 ◽  
Vol 11 (37) ◽  
pp. 2933-2939 ◽  
Author(s):  
A. GHOSH ◽  
P. MITRA
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
String Theory ◽  
Extremal Black Hole ◽  
Classical Action ◽  
Charged Black Holes ◽  
Thermodynamic Entropy ◽  
Black Hole Solutions

For extremal charged black holes, the thermodynamic entropy is proportional to the mass or charges but not proportional to the area. This is demonstrated here for dyonic extremal black hole solutions of string theory. It is pointed out that these solutions have zero classical action although the area is nonzero. By combining the general form of the entropy allowed by thermodynamics with recent observations in the literature it is possible to fix the entropy almost completely.

GRAVITATIONAL COLLAPSE OF A SELF-INTERACTING SCALAR FIELD

2007 ◽  
Vol 22 (01) ◽  
pp. 65-74 ◽  
Author(s):  
RITUPARNO GOSWAMI ◽  
PANKAJ S. JOSHI
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Gravitational Collapse ◽  
Energy Condition ◽  
Dynamical Evolution ◽  
Naked Singularity ◽  
Cosmic Censorship ◽  
Weak Energy Condition ◽  
Scalar Field Models ◽  
Cosmic Censorship Conjecture

We construct and study here a class of collapsing scalar field models with a nonzero potential. The weak energy condition is satisfied by the collapsing configuration and it is shown that the end state of collapse could be either a black hole or a naked singularity. It is seen that physically it is the rate of collapse that governs these outcomes of the dynamical evolution. The implications for the cosmic censorship conjecture are discussed.

scholarly journals Black holes with topological charges in Chern-Simons AdS5 supergravity

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Laura Andrianopoli ◽  
Gaston Giribet ◽  
Darío López Díaz ◽  
Olivera Miskovic
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Hamiltonian Formalism ◽  
Naked Singularity ◽  
Extremal Black Hole ◽  
Pure Gauge ◽  
Static Black Hole ◽  
Abelian Field ◽  
Chern Simons ◽  
Spatial Section

Abstract We study static black hole solutions with locally spherical horizons coupled to non-Abelian field in $$ \mathcal{N} $$ N = 4 Chern-Simons AdS5 supergravity. They are governed by three parameters associated to the mass, axial torsion and amplitude of the internal soliton, and two ones to the gravitational hair. They describe geometries that can be a global AdS space, naked singularity or a (non-)extremal black hole. We analyze physical properties of two inequivalent asymptotically AdS solutions when the spatial section at radial infinity is either a 3-sphere or a projective 3-space. An important feature of these 3-parametric solutions is that they possess a topological structure including two SU(2) solitons that wind nontrivially around the black hole horizon, as characterized by the Pontryagin index. In the extremal black hole limit, the solitons’ strengths match and a soliton-antisoliton system unwinds. That limit admits both non-BPS and BPS configurations. For the latter, the pure gauge and non-pure gauge solutions preserve 1/2 and 1/16 of the original supersymmetries, respectively. In a general case, we compute conserved charges in Hamiltonian formalism, finding many similarities with standard supergravity black holes.

scholarly journals Geodesic motion near self-gravitating scalar field configurations

2019 ◽  
Vol 27 (3) ◽  
pp. 231-241
Author(s):  
Ivan M. Potashov ◽  
Julia V. Tchemarina ◽  
Alexander N. Tsirulev
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Circular Orbit ◽  
Naked Singularity ◽  
Schwarzschild Black Hole ◽  
Null Geodesics ◽  
Naked Singularities ◽  
Test Particles ◽  
Stable Circular Orbit ◽  
Innermost Stable Circular Orbit

We study the geodesics motion of neutral test particles in the static spherically symmetric spacetimes of black holes and naked singularities supported by a selfgravitating real scalar field. The scalar field is supposed to model dark matter surrounding some strongly gravitating object such as the centre of our Galaxy. The behaviour of timelike and null geodesics very close to the centre of such a configuration crucially depends on the type of spacetime. It turns out that a scalar field black hole, analogously to a Schwarzschild black hole, has the innermost stable circular orbit and the (unstable) photon sphere, but their radii are always less than the corresponding ones for the Schwarzschild black hole of the same mass; moreover, these radii can be arbitrarily small. In contrast, a scalar field naked singularity has neither the innermost stable circular orbit nor the photon sphere. Instead, such a configuration has a spherical shell of test particles surrounding its origin and remaining in quasistatic equilibrium all the time. We also show that the characteristic properties of null geodesics near the centres of a scalar field naked singularity and a scalar field black hole of the same mass are qualitatively different.

scholarly journals Can Naked Singularities Exist Without Violating The Laws of Black Hole Thermodynamics?

2021 ◽  
Vol 19 ◽  
pp. 204-207
Author(s):  
Amal Pushp
Keyword(s):  
Black Hole ◽  
Cosmic Censorship ◽  
Black Hole Thermodynamics ◽  
Surface Gravity ◽  
Extremal Black Hole ◽  
Naked Singularities ◽  
The Third ◽  
Physical Singularity ◽  
Third Law ◽  
Cosmic Censorship Conjecture

According to the cosmic censorship conjecture, it is impossible for nature to have a physical singularity without a horizon because if it were to arise in any formalism, for instance as an extremal black hole (Kerr or Reissner-Nordstrom) then the surface gravity κ = 0, which is a strict violation of the third law of black hole thermodynamics. In this paper we explore whether a true singularity can exist without defying this law.

Entropy of near-extremal rotating charged black holes in four-dimensional supergravity from AdS2/CFT1 correspondence

2014 ◽  
Vol 29 (13) ◽  
pp. 1450079
Author(s):  
Jun-Jin Peng ◽  
Qing-Ping Hu
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Central Charge ◽  
Conformal Symmetry ◽  
Black Hole Entropy ◽  
Extremal Black Hole ◽  
Charged Black Holes ◽  
Rotating Black Holes ◽  
Cardy Formula ◽  
Asymptotic Symmetries

We study microscopic entropy of the near-extremal rotating black hole in four-dimensional (4D) 𝒩 = 2 supergravity with four charges set pairwise equal from AdS2/CFT1 correspondence. This correspondence is realized in terms of asymptotic symmetries of the AdS2 geometry and a two-dimensional near-horizon effective quantum theory of residual fields from a dimensional reduction proposed by Robinson and Wilczek. We compute the relevant central charge and derive the microscopic entropy of this near-extremal black hole by Cardy formula. Our results can be extended to more general near-extremal rotating black holes in 4D supergravity. They further support the notion that black hole entropy is generally controlled by near-horizon conformal symmetry.

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